The present invention relates to a yarn winding method, which can be carried out in a yarn winding device, for example, installed in a texturing machine, a draw texturing machine, or a spinning machine.
In a texturing machine or a spinning machine, a yarn is fed at a constant speed, and the thus fed yarn is wound to form a yarn package in a form of a straight cheese or a taper ended cheese. In such yarn winding machines, various winding methods have been proposed in order to maintain the tension in the yarn as constant as possible or to avoid formation of high shoulders or ribbon windings in the wound package.
For example, Japanese Patent Application Laid-open No. Sho 58-17066 proposes to pulsatively vary the traverse stroke so as to perform a so called creeping operation, while the traverse speed is also pulsatively varied at the same frequency as that of the variation of the traverse stroke, and in addition, the time when the traverse speed is maximum and the time when the traverse stroke is minimum are made identical with each other while the time when the traverse speed is minimum and the time when the traverse stroke is maximum are also made identical with each other.
Further, Japanese Patent Publication No. Sho 61-38100 discloses that the winding speed is varied at a constant amplitude and at a constant period which is the same as the period of the traverse speed, while the traverse speed is varied at a constant amplitude and at a constant period upon winding a yarn at a substantially constant speed so as to minimize variation of tension in the yarn and to prevent formation of ribbon windings.
According to the conventional winding methods which have been proposed, there are various problems as set forth below, and the obtained yarn packages are unsatisfactory.
Even if the tension in the yarn being wound can be substantially constant, the yarn cannot be withdrawn at a high speed from the obtained package since high shoulders or ribbon windings may be formed in the wound package.
Contrary to this, should high shoulders or ribbon windings be prevented from being formed in the wound package, the tension in yarn cannot be constant.
Further, the proposed methods can be applied only to wind a yarn in a yarn package having a certain shape.
In addition, yarn quality or hardness of wound package obtained according to the proposed conventional methods may be influenced adversely.
More specifically, when a yarn is wound in the winding method disclosed in Japanese Patent Application Laid-open No. Sho 58-17066, though the tension in yarn may be substantially constant and occurrence of high shoulders may be prevented, the effect for preventing ribbon windings is insufficient depending on the relationships between the varying pattern of the traverse speed and the varying pattern of the traverse stroke since the changes in winding angle during winding operation are small, and accordingly, a yarn package which includes portions similar to ribbon windings may be obtained. When a yarn is withdrawn from a package including such portions similar to ribbon windings, the yarn wound at the portions cannot be smoothly withdrawn at a high speed, and therefore, operational efficiency becomes low.
When the winding speed is varied at a constant amplitude and a constant period which is the same as the period of the traverse speed while the traverse speed is varied at a constant amplitude and a constant period upon winding a yarn at a substantially constant speed as disclosed in Japanese Patent Publication No. Sho 61-38100, variation of tension in yarn can be decreased if an attempt for preventing formation of high shoulders is not carried out, i.e., the traverse stroke is not varied at all. However, when a yarn is wound while the traverse stroke is set completely constant as described above, there is a problem that high shoulders surely occur in the obtained yarn package. In order to prevent high shoulders, if a so called creeping operation is carried out, i.e., if the traverse stroke is varied periodically, there is another problem that the variation of tension in yarn during winding operation is enhanced.